title: Prediction of extracellular proteases of the human pathogen Helicobacter pylori reveals proteolytic activity of the Hp1018/19 protein HtrA.
abstract: Exported proteases of Helicobacter pylori (H. pylori) are potentially involved in pathogen-associated disorders leading to gastric inflammation and neoplasia. By comprehensive sequence screening of the H. pylori proteome for predicted secreted proteases, we retrieved several candidate genes. We detected caseinolytic activities of several such proteases, which are released independently from the H. pylori type IV secretion system encoded by the cag pathogenicity island (cagPAI). Among these, we found the predicted serine protease HtrA (Hp1019), which was previously identified in the bacterial secretome of H. pylori. Importantly, we further found that the H. pylori genes hp1018 and hp1019 represent a single gene likely coding for an exported protein. Here, we directly verified proteolytic activity of HtrA in vitro and identified the HtrA protease in zymograms by mass spectrometry. Overexpressed and purified HtrA exhibited pronounced proteolytic activity, which is inactivated after mutation of Ser205 to alanine in the predicted active center of HtrA. These data demonstrate that H. pylori secretes HtrA as an active protease, which might represent a novel candidate target for therapeutic intervention strategies.
authors.affiliation: Goethe-University, Institute of Cell Biology and Neuroscience / CMP, Frankfurt am Main, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Löwer
authors.forename: Christiane
authors.initials: C
authors.lastname: Weydig
authors.forename: Dirk
authors.initials: D
authors.lastname: Metzler
authors.forename: Andreas
authors.initials: A
authors.lastname: Reuter
authors.forename: Anna
authors.initials: A
authors.lastname: Starzinski-Powitz
authors.forename: Silja
authors.initials: S
authors.lastname: Wessler
authors.forename: Gisbert
authors.initials: G
authors.lastname: Schneider
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002364:Caseins / Q000378:metabolism; D019295:Computational Biology; D005110:Extracellular Space / Q000201:enzymology / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D016480:Helicobacter pylori / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000235:genetics; D020543:Proteome / Q000032:analysis; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002364:Caseins; D021382:Protein Sorting Signals; D020543:Proteome; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases